class_docstr: A helper class that represents input string that to be modified.
  
  Text that Sample contains parsed in data set,
  ``TextField`` provides multiple methods for Sample to modify.
  
  Support sentence level and word level modification,
  default using word level API.
docstr: Get POS tags.
  
  Example::
  
      given sentence 'All things in their being are good for something.'
  
      >> [('All', 'DT'),
          ('things', 'NNS'),
          ('in', 'IN'),
          ('their', 'PRP$'),
          ('being', 'VBG'),
          ('are', 'VBP'),
          ('good', 'JJ'),
          ('for', 'IN'),
          ('something', 'NN'),
          ('.', '.')]
  
  :return:  Tokenized tokens with their POS tags.
docstr_tok: ["Get","POS","tags",".","Example",":",":","given","sentence","'All","things","in","their","being","are","good","for","something",".","'",">",">","[","(","'All","'",",","'DT","'",")",",","(","'things","'",",","'NNS","'",")",",","(","'in","'",",","'IN","'",")",",","(","'their","'",",","'PRP","$","'",")",",","(","'being","'",",","'VBG","'",")",",","(","'are","'",",","'VBP","'",")",",","(","'good","'",",","'JJ","'",")",",","(","'for","'",",","'IN","'",")",",","(","'something","'",",","'NN","'",")",",","(","'",".","'",",","'",".","'",")","]",":","return",":","Tokenized","tokens","with","their","POS","tags","."]
code: def pos_tagging(self):
      r"""
      Get POS tags.
  
      Example::
  
          given sentence 'All things in their being are good for something.'
  
          >> [('All', 'DT'),
              ('things', 'NNS'),
              ('in', 'IN'),
              ('their', 'PRP$'),
              ('being', 'VBG'),
              ('are', 'VBP'),
              ('good', 'JJ'),
              ('for', 'IN'),
              ('something', 'NN'),
              ('.', '.')]
  
      :return:  Tokenized tokens with their POS tags.
  
      """
      if not self._pos_tags:
          pos_tags = [
              pos for w, pos in self.text_processor.get_pos(self.words)
          ]
          if len(pos_tags) != len(self.words):
              raise ValueError(
                  f"POS tagging not aligned with tokenized words"
              )
          self._pos_tags = pos_tags
  
      return self._pos_tags
  
imports: from .field import Field
  from ....common.utils.list_op import *
  from ....common.preprocess.en_processor import EnProcessor
  from ....common.settings import ORIGIN, TASK_MASK, MODIFIED_MASK
label_desc: Use image node_id 22 for calling the TextField obj's underlying member method code with example usage: obj.pos_tagging() and returns: self